The Federal Election Commission does serious issues. It does complex debates over mind-numbing campaign laws. It does not do funny. But now the agency finds itself the target of a very public joke by television comedian and provocateur Stephen Colbert, who is set to testify Thursday on his tongue-in-cheek bid to form an eponymous “super PAC” for the 2012 election season. The host of “The Colbert Report” on Comedy Central has spent months riffing on the notion of a political committee dedicated to his own enrichment, part of a broad satire poking fun at court rulings allowing corporations to spend unlimited amounts of money on elections.